17. Have you ever seen this brief presentation by Tom Scott: "Flashmob gone wrong"?

This is so worth the few minutes of your time it takes that it's not even funny. You and everyone else. Because in that talk is the kernel of the power of the internet that we saw on display in this "crowdsleuthing". And while the results are less fatal than the situation described in the video above, they are both situations where awful, awful things can happen...in a flash.